King County Interbay Pump Station Upgrade

Project overview

The Interbay Pump Station Upgrade, which increased the station’s pumping capacity from 122 MGD to 133 MGD, was completed ahead of schedule with a low change order rate. The Vanir team provided technical engineering expertise, schedule review and analysis, RFI/Submittal/Document control and change management. Construction had to be performed while maintaining the 24/7 operation; we worked collaboratively with King County Operations staff to schedule and coordinate the work efficiently.

  • Construction included removal and replacement of the three existing 36” raw sewage pumps and drives with new pumps with high-efficiency motors on VFDs
  • Within the building, the 36” steel discharge piping was removed and replaced and the four existing 36” ball valves were reinstalled
  • Structural modifications were made to the existing structure
  • Mechanical work included a utility water pump, nonpotable water pumps, an instrument air compressor and sump pumps
  • Electrical work included replacing the existing 4160 volt and 480 volt switchgear, constructing a generator building and the purchase and installation of one 4160 volt generator
  • HVAC work included replacement of fans, air ducts, the addition of a heat pump and unit heaters and installation of an on-site odor control unit
  • The existing bridge crane was replaced and a new hoist installed
Seattle, Washington
King County



Stellar J Corporation

Construction Cost
$12 Million
Completion Date